Relatives of U.S. military personnel in Afghanistan and other callers phoned quake experts early this week, anxious to know whether the military bombing campaign triggered Monday's earthquake in Afghanistan . . .
Where the Earth makes war on itself Asia's tectonic plates play bumper cars -- and people get hurt Keay Davidson, Chronicle Science Writer Wednesday, March 27, 2002 �2002 San Francisco Chronicle URL: <http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/03/27/MN149594.DTL> No, the bombing of Afghanistan did not trigger Monday's killer quake. What did trigger it is the pushing and shoving of immense tectonic plates as they ram together in Central Asia, fissuring the crust into a thicket of fault lines, experts say. The result is one of the world's shakiest, deadliest regions. Even a moderate Afghan quake can topple the omnipresent mud homes and kill thousands of people. Relatives of U.S. military personnel in Afghanistan and other callers phoned quake experts early this week, anxious to know whether the military bombing campaign triggered the seismic slaughter. "I've been answering that question all day. Even a reporter from Afghanistan called and asked if the bombing might have done it," said Waverly Person, a geophysicist at the United States Geological Survey's National Earthquake Information Center in Golden, Colo. "There is no way the bombings caused the earthquakes in that area," Person declared. "This is one of the highly seismic parts of the world, and (the quake) is not unusual at all." Agreement came from one of the top U.S. seismologists who once did field work in Afghanistan. "A magnitude-6 earthquake is more energy than the largest atomic bomb we've been allowed to test since the Test Ban Treaty of 1963," said the scientist, Lucy Jones, who works at the USGS branch in Pasadena. Preliminary data indicate Monday's quake -- which struck just before 7 a. m. PST -- measured about 6.1, Person said. Its epicenter was about 100 miles north of the Afghan capital, Kabul. The quake "hypocenter" -- the precise underground point of rupture on the fault -- was unusually shallow, between 2 and 5 miles deep. No one knows which fault is to blame for Monday's seismic event, scientists said. Quakes are routine nightmares in Afghanistan. On March 3, about 100 people died in a temblor whose epicenter was almost 80 miles to the east-northeast of Monday's epicenter, according to Person and David Oppenheimer of the USGS office in Menlo Park. Likewise, in February 1998 a 5.9-magnitude quake killed more than 2,300 people in Afghanistan. The following May, a 6.6-magnitude quake killed 4,000, Person said. Quakes and volcanic eruptions are the best known consequences of plate motion. Like a polar ice floe broken into broad, flat slabs of ice, Earth's crust is broken into slabs of rock called plates. These slabs slowly move around the Earth. Some plates grind horizontally past each other, as along California's San Andreas Fault. Some plates are so dense that, lacking buoyancy, they dive beneath other slabs, forming "subduction" zones that bristle with volcanoes and quake activity, as along the Pacific Northwest coast. In Central Asia, though, two "convergent" plates -- the Indian and Eurasian -- have roughly the same density, and neither dives beneath the other. As a result, they ram together at an average speed of 1.8 inches a year over millions of years. This forces the crust to buckle and rise to spectacular heights. The best- known example: Mount Everest. "The rocks there have been put through hell and back -- like the people," Jones said of Afghanistan. "Rocks are turned over and over and over each other. " E-mail Keay Davidson at [EMAIL PROTECTED] �2002 San Francisco Chronicle Page A - 14
